The present invention relates to a tappet in an internal combustion engine and a method of manufacturing it.
For example, to increase wear resistance of a conventional tappet, as shown in FIG. 8, a helical groove 13 is formed on the outer circumferential surface of raw material for a tappet to make a core material 15, the surface of which is thermally sprayed by wear resistant material such as Fe metal to form a coating layer 17 which covers the helical groove 13. The outer circumferential surface of the coating layer is ground to form a cylindrical portion 18, the end 19 of which is chamfered.
However, at the chamfered end of the tappet, as clearly shown in FIG. 9, the cylindrical wear resistant coating layer 17 in which the groove 13 of the core material 15 is embedded is slightly left as a fine string-like portion 16, which is likely to peel off as small pieces.